The present invention relates generally to biosensor capacitors. In particular, the present invention provides a biosensor capacitor connected to a bond pad.
Referring to FIG. 1 and FIG. 2, a cross-section view (FIG. 1) and a top down view (FIG. 2) of a known biosensor capacitor 10 are shown. Known biosensor capacitor 10 includes an oxide layer 12 over a silicon layer 14. An opening in the oxide layer 12 includes a gold layer 16 at the bottom of the opening. A gold counter electrode 18 surrounds the opening at the top of the oxide layer 12. A photoresist layer 20 surrounds the gold counter electrode 18.
Deoxyribonucleic acid (DNA) sensing may be performed using known biosensor capacitor 10 to detect the presence of certain types of biological substances in a sample. Probe (also known as “receptor”) DNA is placed on the gold layer 16. An electrolyte sample 22 is placed over the gold layer 16 and the probe DNA. The probe DNA is negatively charged. An applied positive charge to the gold layer 16 will attract the probe DNA. If the electrolyte sample includes a target DNA, the target DNA will hybridize with the probe DNA. The physical characteristics of the hybridized DNA may be detected using a measuring device 24, for example, fluorescence detectors, capacitors, field effect transistors, magnetic sensors, or the like.